Overview of Carbon Dioxideand d Methane Cycle Research

Transcription

1 Liukang Xu LI COR Biosciences, Lincoln Nebraska USA Overview of Carbon Dioxideand d Methane Cycle Research Apr 18, 2013 at 南京信息工程大学

2 Discussion Topics Climate change and global warming Causes of climate change Large scale research Global observation network Ecosystem scale methods chamber based based flux measurement ecosystem flux Methane flux

3 Courtesy of IPCC

4 New Denver Glacier British Columbia, Canada Glacier retreat!

5 Sea Level Rise

6 Hydrological Cycle Disrupted Spring of 2010 that affected Yunnan, Guizhou, Guangxi, Sichuan, Shanxi, Henan, Shaanxi, Chongqing, Hebei and Gansu.

7 Hydrological Cycle Disrupted Flooding in China 2010 Summer

8 Damage by 2010 flood Duration May to Sept 2010 Fatalities Damages: dead, missing $ 51.4 billion Areas affected: 28 provinces, autonomous regions and municipalities Flooding in China 2010 Summer

9 2012 Arizona dust storm

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13 Atmospheric CH 4 Growth Trend

14 Greenhouse Effect Radiative forcing is usually quantified as the rate of energy change per unit area of the globe as measured at the top of the atmosphere due to the presence of the gas species. When radiative forcing is evaluated as positive, the energy of the Earth atmosphere system will ultimately increase, leading to a warming of the system. IPCC 2007, Changes in Atmospheric Constituents and in Radiative Forcing

15 Causes of Atmospheric CO 2 Increase Burning fossil fuel

16 Causes of Atmospheric CO 2 Increase Burning fossil fuel CO2 C

17 CO 2 uptake CO 2 Release A Healthy Forest Ecosystem

18 Causes of Atmospheric CO 2 Increase; Deforestation No more CO 2 uptake CO 2 Release Deforestation

19 Global Energy Flow (W m 2 ) This component is affected Trenberth et al., 2009

20 2.0 to 2.5 万年 140 年 Lüthi et al., Nature. 453:

21 地球的命运在我们人类的手中 THE EARTH IS IN OUR HANDS

22 Questions scientists are trying to answer are: What are the sources, sinks of CO 2, CH 4, N 2 O? What are the factors that regulate these source and sink strength? Atmospheric CO 2, CH 4, N 2 O trend? What kind of impact on climate from the changes in atmospheric CO 2, CH 4, N 2 O concentrations?

23 Global Carbon cycle Atmospheric monitoring Ecosystem exchange Industrial monitoring Soil flux Leaf level exchange Sea surface exchange

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25 Atmospheric CH Growth Trend 4 Dlugokencky et al., Phil. Trans. R. Soc. A 369:

26 Methanogenesis Produced in anaerobic environments C 6 H 12 O 6 3CO 2 +3CH 4 Formed at low Eh (Redox potential)< 200 mv

27 Methane Sources Wetlands Rice fields Biomass burning Domestic animals Other Landfill Coal Mining Oil and Gas Insects

28 Isotopic monitoring i (CH 4 ) Source 13 C ( ) Ambient background air 47 Wetland 70 to 60 Savanna grassland burning 20 to 15 Boreal forest burning 30 to 25 Ruminants digesting C 4 species 55 to 50 Ruminants digesting C 3 species 65 to 60 Coal and natural gas 34 to 35 Rice field 62 R= 13 C/ 12 C

29 Keeling plot to identify the source Pataki et al., The application and interpretation of Keeling plots in terrestrial carbon cycle research. Global Biogeochemical Cycle. 17:1022.

30 Research method for ecosystem: Chamber based flux measurement Pump 6 Gas IRGA analyzer y = x R² = (ppm) CH 4 3 V Time (s) F CH 4 V A C t

31 Requirements for chamber based flux measurement F CO2 =g (CO 2 soil CO 2 chamber ) 1. CO chamber 2 = CO air 2 2. CO 2 soil not disturbed 3. P Chamber = P ambient 4. Good mixing inside chamber 5. No disturbance to soil moisture, temperature or radiation balance

32 Research method for ecosystem: Eddy covariance flux measurement for F CO2,, F CH4,, LE, H w (m/s) W 4 CO2 California Grassland DOY , T Time (s) O2 (mmol/m3) C Data of Xu and Baldocchi Example of 10 Hz real data! Picture courtesy of Dr. Youngryel Ryu

33 Research method for ecosystem: Eddy covariance flux measurement for F CO2, F CH4, LE, H WIND F aw' ' s '

34 Example pe of instrumentation at a flux station

35 Advantages of the EC Method over other methods It is a direct measure of the flux density, it is in situ, it introduces no disturbance on the system it is quasi-continuous, and represents a large upwind area.

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37 Transport of methane to atmosphere 1. Convective flow through plant conduits 2. Diffusion across the air water boundary layer 3. Water convection 4. Direct injection into the air via bubble bble transport

38 Convective flow through plant conduits Phragmites Australis

39 Convective flow through h plant conduits Temperature Response?? Kim et al., Global Change Biology, 1998

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41 Diffusive CH 4 flux Barker et al., Global Biogeochemical Cycle, 1988.

42 Via. Water convection Sahlee et al., 2011

43 Direct injection into the air via bubble bbl transport t Walter et al., Nature 2006

44 CH 4 flux vs. barometric pressure studies in the literature Mattson, Likens Air pressure and methane fluxes, Nature, 347 At Mirror Lake, New Hampshire, we observed that sporadic methane bubble releases (ebullition) from the sediments were correlated with changes in local air pressure. McQuaid, Mercer Air pressure and methane fluxes, Nature, 351 A similar phenomenon has been known to mining engineers in the UK for more than 250 years.

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46 Changes in barometric pressure and landfill CH4 emission 120 CH 4 emission Pressure 100 CH ssion ( mo ol m -2 s -1 4 emis ) /16/10 11/21/10 11/26/10 12/01/10 12/06/10 12/11/10 12/16/10 Pre essure (kpa a) Date (mm/dd/yy) Xu et al., Impact of Changes in Barometric Pressure on Landfill Methane Emission. Submitted to Global Biogeochemical Cycle.

47 Coherence between barometric pressure and CH 4 emission A wavelet coherence analysis

48 o X Y Variable Time y = x R 2 = Y X

49 Rice paddy CH 4 flux Very few long-term CH 4 flux study from rice paddy in the literature 90% of rice production is from Asia?

50 Photosynthesis and methane emission from rice field Hatala et al., 2012.Geophysical Research Letters, 39:

51 Methane Sinks 1. Reaction with hydroxyl y radical in troposphere p and stratosphere (~95%) CH 4 +OH CO 2 +H 2 O 2. Dry soil oxidation (~5%)

52 Summary Global warming, climate change Atmospheric CO 2 and CH 4 concentration increasing Increasing rate unprecedented More frequent extreme weather events, including drought, flood, hurricane etc. Research on CO 2, CH 4 sources and sinks Mitigation i i and adaptation

53 谢谢 Thank You